Index NHI Toby OGeen PhD Soil Resource Specialist in Cooperative Extension Department of Land Air and Water Resources University of California Davis NHI is a valuable tool to identify the relative differences in nitrate leaching hazard for soils irrigation schemes and cropping syst ID: 329379
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A Vision for a Revised Nitrate Hazard Leaching Index (NHI)
Toby O’Geen, Ph.D.Soil Resource Specialist in Cooperative ExtensionDepartment of Land, Air and Water ResourcesUniversity of California, DavisSlide2
NHI is a valuable tool to identify the relative differences in nitrate leaching hazard for soils, irrigation schemes, and cropping systems
Convenient
Easy
Representative of CA’s cropping systems and soilsSlide3Slide4
Shortcomings of the Current NHI
Soil index ratings have potential bias as they are based on the opinion of 3 individuals.Not all soils are rated.The experts have retired (1) and/or (2) moved on to other positions making updates challenging.NHI lacks transparencyDoes not consider climate
NHI rates soil series not components of map unitssoil series have a range in characteristics that is documented by map units e.g. Yolo silt loam; Yolo silty clay loam, Yolo loam; Yolo loam clay substratumSlide5
Shortcomings of the Current NHI
Soil index ratings have potential bias as they are based on the opinion of 3 individuals.Not all soils are rated.The experts have retired (1) and/or (2) moved on to other positions making updates challenging.NHI lacks transparencyDoes not consider climate
NHI rates soil series not components of map unitssoil series have a range in characteristics that is documented by map units e.g. Yolo silt loam; Yolo silty clay loam, Yolo loam; Yolo loam, clay substratumSlide6
Masks the complexity of soil
survey dataOther Shortcomings of the Current NHI
What do you choose?
Dominant soil
Limiting condition
Area weighted average
Dominant conditionSlide7
Goal: Develop a Data-Driven, Revised Nitrate Leaching Hazard Index
Parameterize HYDRUS with soil survey data to model nitrate flux over irrigation, crop, N-management and BMP scenarios.
Develop a data-driven hazard rating based on model results.Create interactive web-based apps that report NHI ratings and place-based BMPs, and possibly nitrate flux estimates.Slide8
Outcomes of a Revised NHI
Less subjectivityGreater transparencyWill generate ratings for every soil component within soil
map units. This is needed for watershed scale analysis.Wide spread adoption via interactive web-based appsCapability of generating nitrate flux beyond the root zone (quantity time-1 area-1) useful for evaluating BMP’s and cropping system scenarios.
Can be linked with
groundwater models and other decision support tools
.Slide9
What would it look like?
Integrate with SoilWeb: Easy to use and link with info.
NHI
Lettuce
Almonds
Grapes
Alfalfa
Furrow
80
60
15
5
Sprinkler
70
50
-
5
Drip
-
20
5
0
BMPs
25
10
0
0
http://casoilresource.lawr.ucdavis.edu/gmap/Slide10
Apps have interactive mapping capabilities that could display spatial extent of NHI.
Flexibility in Data DeliverySlide11
Data for Multiple
Scales: Field to Regional Scenarios
e.g. change in nitrate loss beyond the root zone considering 25% increase in adoption of improved irrigation technology.Slide12
Soil Agricultural Groundwater Banking Index
Tradeoffs
between maximizing water quantity and maintaining water quality need to be evaluated.Tools need to harmonizeSlide13
Thank You
http://casoilresource.lawr.ucdavis.edu/soilweb/Slide14Slide15Slide16